Helicopter rotor construction



Oct. 7, 1952 P. M. LEWIS HELICOPTER ROTOR CONSTRUCTION 4 Sheet s-Sheet 1 Filed Sept. 9, 1947 IN v/v TOP: P4 UL M LEW/5 BY MS A TTOEAIEYS hAP/P/ ,Mecafsrm HARRIS Patented Oct. 7, 1952 HELICOPTER ROTOR CONSTRUCTION Paul M. Lewis, Chicago, Ill., assignor to Peninsular Metal Products Corporation, Detroit,

This invention relates to, aeronautical apparatus.

j ,I object of the invention is to provide in an aircraftof the helicopter type means for simultaneously varying the pitch of the individual blades ofeach rotor and including means for adjustably interconnecting the blades for unitary rotation about the axis of the rotor while permitting relative rotation on their respective axes to vary their pitch, said interconnecting means jalsoserving to resist centrifugal force exerted I of illustration. In the drawings:

. Fig. 1 is a side elevational view of a helicopter "constructed in accordance with the present invention;

, Fig. 2 is a front elevation of the structure shown in Fig. 1;

j Fig. 3 is an enlarged fragmentary view of the nose end of the helicopter showing the manually operable controls;

Fig. 4 is an enlarged front elevation of the nose. of the helicopter with parts of the nose broken away to disclose the internal parts;

Fig. 5 is a further enlarged cross-sectional view of the'driving means for one of the power rotors,

taken on line 5-5 of Fig. 1; and

Fig. 6 is a cross-sectional view taken on line In the form of helicopter construction shown in the drawings, a fuselage I5 of conventional construction is shown as being provided at its forward portion with a suitable removable transparent hood I5 normally enclosing a cockpit in which a seat I'I for a pilot and passengers is provided adjacent to appropriate control mechanism hereinafter described.

Arranged laterally of the forward portion of the fuselage I5 are two power rotors I8 disposed .,.in generally horizontal positions ongenerally .vertical axes, and at the rear of the fuselage is disposed, a single, preferably relatively small stabilizing rotor 20 mounted in a special tai1- piece 22 of the fuselage I5.

The two rotors I8 are carried, respectively, in vertically extending narrow housings 24 which enclose means constituting the axes about which the rotors I8 operate. The housings 24 are rotatably carried upon transversely extending cantilever beams 25 of streamlined outline resembling airfoils which are rigidly secured to the upper portion-of the fuselage I5. Obviously, any suitable additional bracing means (not shown) may ,be employed if necessary or desirable. The hous- 'ings 24 are adapted to be rotated about an axis Mich., a corporation of Michigan Application September 9, 1947, Serial No. 772,953

7 Claims. (01. 170--160.42)

extending centrally of the hollow beams 25, such motion being transmitted to the housingsf by sleeves 26, the outer ends of wh'ichare; rigidly connected to the, lower ends of the housings by box-like casings 21 and coupling meinbers2'8. The sleeves 26 are mounted for rotation wi the beams 25 by means of suitable bearingsja'nd secured to each sleeve is a depending arm 30 (Fig. 3). A pair of endlesscontrol cables 3 I 'anld 32 pass around forward and aft pulleys 33, 34 and 35, 36, respectively, arranged within the cockpit I6 at the sides thereof. The forward 'puuey 33 and 34 are carried by shafts 38 and 39, respectively, extending transversely of the cockpitand .suitably journaled in bearings therein, (Fig. 4).

Handwheels 40 and 4| are fixed 'to-the shafts'38 and 39 and are located in a position to be readily rotated by the pilot. The cables 3i and 32'--ajre joined to the lower ends of the arms 30 "so that 7 when the'handwheels are rotated manually the sleeves 26 will be turned to, cause therotor housings 24, together with therotors I8, to betilted forwardly or rearwardly, depending upon the direction of rotation of the handwheels. By providing separate control means for each rotor tilting mechanism, as above described, the rightand left-hand rotors maybe tilted independently of each other, and in opposite directions'if desired, in maneuvering the helicopter. Theax'is of the rear rotor 20 is bermanentlytilted-forwardly as shown in Fig. l to improve its stabilization effect and at the same time permits a limited amount of propulsive effort.

The helicopter is adapted to rest upon an move along the ground, as when taxiing, and'a pair of ground wheels 43 are provided for this purpose. The wheels 43 are rotatable at the lower ends of struts 44 depending'from spars 45 which project laterally from the fuselag'e adjacent the bottom thereof, the spars being preferably of airflow cross-section as shown in Fig. 1. The rearward end or tailof the craft maybe similarly supported by a tail-wheel 46.01: suitable skid means.

As shown in Figs. 3' and 4, the power means for rotating the rotors I8 consists of an internal combustion engine located within the fuselage I5 of the helicopter and may be of any suitable type. Sufiice it to statethat the engine5ll has a vertical output or drive shaft.5l, to the upper end of which is keyed a bevel gear 52. A clutch, such as indicated generally at 50', may help cluded in the drive shaft 5I. -The bevel gear52 meshes with a larger bevel gear 53 keyed to a shaft v54 extending transversely of the fuselage I5 within the sleeves 26 and rotatable in bearings 55 and 56 therein, the bearings 56 being of the combined axial and radial thrust roller type. The transverse shaft 54 carries a bevel gear-158 at each of itsends for driving the individual rotors I8. Since the rotors l8 are of identical .tions.

acts to stabilize the craft.

the other sleeve.

construction, only one is herein shown and de scribed in detail.

Referring to Figs. 5 and 6, each tubularrotor housing24 has its lower end secured within a vertical opening in the casing 21 and carries roller bearings 59 and 50 within its upper and lower ends, respectively, for rotatably supporting a tubular sleeve or torque tube 62. A relatively large bevel gear 63 is keyed to the lower end of the sleeve 62 and the hub of this gear is rotatable in the bearing '60. Rigidly secured to the upper end of the sleeve 62 is a hollow hub member 64 which has a tubular extension 65 rotatable in the upper bearing 59, the extension 65 being suitably connected to the upper end of the hollow shaft 62. It willbe apparent from the above that during operation of the engine 50 the transverseshaft 54 is rotated through the medium of the gears 52 and 53 and the shaft 54, in turn,

drives the vertical tubes 62 and hub members 64 by means of the meshing gears 58 and 63. Through this arrangement of parts the rotor tubes 62. and hub members 64 at opposite sides of the fuselage [5 are. rotated in opposite di ec- A suitable .clutch (not shown) may be provided for connecting and disconnecting the drive from the engine 50 to the shaft 54.

Each hub member 64 is split horizontally to provide two mating parts which are secured together by means of bolts fit (Fig. 5). Each hub member 64 is also provided with a pair of op posite radial tubular bosses '6'! in which are antifriction bearings 68 for rotatably supporting sleeves 65 whichhave inner closed ends l0. Held inv the sleeves B9 are the inner circular spindles ll of power rotor blades 12, a plurality of screws 13 passing throughholes in the spindles is of the sleeves G9 and screwed into threaded holes in the spindles 1| of the blades 12 serving to rigidly connect these parts for unitary turning movement in the bosses 61 in the manner and for the purpose to be later explained. It will be observed by reference to Fig. 2 that the blades 12 of each rotor l8are inclined upwardlyfrom their axis of revolution to effect a dihedral which The rotor blades 72 may be of a suitable airfoil contour in cross section as usually provided in conventional helicopters, the present invention not being limited to any specific form of blades.

Duringthe relatively fast revolution of the rotor blades 12 about the axis of the rotor 58 the blades are subjected to considerable centrifugal force tending to move them radially outward inthe direction of their longitudinalaxes .and' to prevent such movement and to relieve the strain on the blades, this invention provides means for interconnecting the blades in such a manner that the centrifugal force exerted upon each blade is counteracted by the similar force exerted upon the other blade so that these'forces are, in effect, balanced out or nullified. Referring to Fig. 6, the inner end of. each. sleeve 69 is provided with a pair of diametrically spaced. arms I4, the pairs of arms of each sleeve being set at substantially right angles to the pairs of'arms of Adjacent their. freev ends, the pairs of arms 14 of each sleeve 69- have aligned, broached holes 15 having serrations for receiving the ends of a fluted pin 16 which are held in place therein by snap-rings Tl. Each fluted pin 16 passes through the fluted bore of an eccentric 18 which is interposed between the arms 14.

one with the other, so that centrifugal force acting upon each rotor blade 12, when the rotor i8 is rotating, will be counteracted by centrifugal force imposed upon the other blade :in the opposite direction. Through this arrangement of parts the radial thrust exerted upon the rotor blades in a direction away from their common axis ofrevolution is absorbed by the eccentric 78, pins 15 and arms M and thus strain on the bearingsfiil and other parts is entirely avoided. In order to adjust and maintain the eccentrics 18 in interengaging relationship, one or both fluted pins it may be withdrawn from its respective bearings in the arms 74 and one of the eccentrics turned with respect to the other eccentric, after which the pin is re-inserted and secured in the holes 15 to maintain the adjustment. The eccentric interconnecting means serves a second function, in that it permits adjustment of the rotor blade sleeves 63 toward and away from each other, to establish proper cooperation between the operating partsof the blade adjusting mechanism, to be described hereinafter.

' The rear stabilizing rotor 29 is similar in construction to the power rotors l8, previously described, and therefore will not be described in detail. Suffice it to explain that the rotor 20 is provided with a pair of blades which are connected to and rotated by a central rotor hub member suitably journaled to rotate i a bearing sleeve 82 located in the tail portion 22 of the fuselage 5. The drivin means for the rotor 23 includes a shaft 83 having a bevel gear 84 which meshes with a similar gear 85 on the rearward end of a drive shaft 86 extending longitudinally within the fuselage it. The forward end of the shaft 85 carries a bevel gear 87 which meshes with a smaller bevel gear 88 fast on the transverse shaft 55. It will be apparent that when the transverse shaft 54 is rotated the rotor 20 is driven thereby through the medium of the gears and shafts above described at a reduced rate of speed. The axis of the shaft 83 and hub member 81 is inclined forwardly with respect to the vertical or to the longitudinal axis of the fuselage l5 and this serves to stabilize the fuselage and at the same time adds to the propelling power.

It has been stated that the rotor blades 12 are adapted to be turned on their longitudinal axes to vary their pitch and this is accomplished by means to be next described. Surrounding the inner end of each rotor sleeve 69 and secured thereto by screws 90 is a rin 9| formedwvitha segmental bevel gear 92, the teeth of which mesh with the teeth of a bevel gear 93 arranged between the two gears 32 and rotatable on a substantially vertical axis. As shown in Fig. v6, the gear 93 is provided with an elongated hub 94 which is rotatable in a ball bearing 95 on the rotor hub member fi l. The hub 94 of the gear 93 is provided with a' screw-threaded bore 96 which is adapted to receive the upper screw-threaded end S7 of a tubular spindle 98. As shown in Fig. 5,.the lower end of the spindle 98 is rotatable in a ball bearing 99 held in a cup-shaped connector element Hi6 which, in turn, is fastened to the upper end of a tubular actuating shaft I02. The shaft W2 is arranged coaxial with the spindle 98 and is provided with external screw threads at its lower end which engage with the internal screw threads of a cylindrical nut member 103 rotatable in a boss Hi l of the casing 27. The nut member Hill is retained in the boss I04 and held against axial displacementby reason of a peripheral flange I05 on the member engaging an annular recess I06 in the boss. To the lower end of the-nut member I03 is secured a sprocket I01 which is adapted to be manually rotated by the pilot through means later described to adjust the pitch of the rotor blades 12. Any suitable I means may be provided for preventing relative rotation between the spindle 98' and the tubular shaft 82, Fig. 6 illustrating this means as comprising a transverse pin I08 held in and'arranged with its ends projecting radially outward from the spindle 98 and through elongated slots I09 .in the shaft 62. It will be apparent that through this construction, the spindle 98 may move axially within the tubular shaft 62 but is withheld against rotation relative to the shaft. When the spindle 98 is moved axially within the shaft 62 its screw threads 91, due to their engagement with the screw threads 90 of the gear 83, act to rotate the gear 83, the directionof rotation of the gear depending upon the direction of axial movement of the spindle. Rotation of the bevel gear 93 is transmitted to the gear segments 82 and the sleeves 68 are turned in the bearings 88. The

rotor blades I2 thus are angularly adjusted to control their pitch, it being noted that through the gear connection .93, 82 the blades are turned ontheir longitudinal'axes in opposite directions which is the necessary result. The shaft I02 is similarly held against rotation by a pin-and-slot connection IIO, III so that when the nut member, I03 is rotated the shaft I02 is moved vertically only. The two-piece construction I02, 98

r isnecessary to permit the spindle 98 to rotate with the gear 93,hub member 61 and tubular drive shaft 62 during operation of the rotor I8.

.As previously explained, the two power rotors I8 are of similar construction, the drivin and adjusting parts described above in connection with one rotor being duplicated in the other power rotor. The rotor-blade pitch adjusting mechanism described above is controlled manually-bythe pilot within the cockpit I6 through means to be next described. Mounted to pivot on spaced pins I I5 and H6 having their axes extending parallel to the longitudinal axis of the fuselage are control levers II'I andII8. Attached to the respective levers Ill and H8 by pins II9, I andI2I, I22

are the opposite ends of cables I24 and I25. Each of the cables I24 and I25 extends around pulleys I26and I21 and its outer looped end is provided with a section of chain I28 (Fig. 5) which passes around the sprocket I0'I. It will be apparent from the above that when the control levers, Ill and H8 are tilted on their respective pivots H5 and I I6; in the manner indicated by, dot-anddash lines in Fig. 4, the chain sections I28 act to rotate the sprockets I01 to tur the nut members I03 to adjust the pitch of the power rotor blades 12 through the means before described. 3

The pivot pins H5 and H8 are carried by a transverse shaft I30 which is rotatable in bearings I3I and which is provided with a depending arm I32. An endless cable I33 is looped around a forward pulley I34 and passes over pulleys I35 and I36 (Fig. 1) and its rearward end is provided with a chain section I38 which is looped around be identical with the pitch adjusting mechanism Operation In operating a helicopter constructed according to the improvements of the present invention, the engine 50 is started in any desired man ner, the clutch 50' (Fig. 4) having been first disengaged by any suitable means, not shown. After the engine" 50 has been properly warmed, the clutch 50' is again engaged. The pitch of the blades I2 will have been adjusted to a suitable position, the axes of the rotors I8 will have "been disposed in vertical position, and the blades of the rear rotor 20 will have been adjustedabout their longitudinal axes for proper stabilization of the ship during ascent.

Ascent to a proper height having been effected, forward motion is best accomplished by tipping the axes of the rotors I8 forward, whereby to obtain a proper angle of attack by the blades 12'. This is accomplished by tipping the housings 24 so that their upper ends move forward, the motion being accomplished by rotating the sleeves 26 to which the housings 24 are secured through the medium of the arms 30, cables 3|, 32 and hand wheels 40, M which are located adjacent the pilot's position in the cockpit I6. When the blades I2 of the rotors I8 are properly adjusted about their longitudinal axes for for ward flight, the tipping of the rotors I8 bodily forward causes the blades which are movingfor-iward in the common or overlapping portionof the paths of the rotors to move in a substantially horizontalplane. The same adjustment causes the blades to assume a steeper position as'they rotateinto the outermost portions of their paths; as a result of which the greater angle of attack produces greater propelling action. In other words, the flattened blades passing through the common portion of the paths of the rotors tend to slip forward through the air, whereas-the blades moving rearward in the outermost portions of their paths attack the airpositively at a steep angle to obtain maximum propelling effect. By reason of the inter-connection ofithe rear rotor 20 by means of the shaft 86 and its connection with the bevel gear 88, proper stabilization of the tail of the ship isobtainedmThe permanent tipping forward of the {axes of the rotor 20, as indicated in Fig. l, improves its stabi lization effect and at the same time permitsat least a limited amount of propulsive work.

Maneuverability of the ship is readily effected by adjustment of the various blades 12 -ofthe power rotors I8 and the blades 80 of the stabilizing rotor 20 about their longitudinal axes; For example, a turn to the right may be accomplished when the axes of the rotors I8 are tipped forward in propelling position by leaving the blades of the left rotor in driving position and rotating the blades of the right rotor about their longitudinal axes so as to reduce the driving effect of the right rotor I8. Such adjustment of the various blades of the right hand rotor I8 about their longitudinal axes is accomplished by manipulation of the right hand control handle II'I. Tilting of the handle III about its pivot pin II5 acts through the cable I24 to rotate the sprocket I0'I andthe nutv member I03 to which the sprocket is secured; Rotation of the nut member I03 causes the screw shaft I02 and spindle 88 to feed upwardly and through the interengagement of the spiral, thread connections 97, 96 the bevel gear 83 is turned through a part of a revolution to im-' 7 part .zopposite. rotary motion tothe twov gear: seg ments 92. Thus the rotor blades 12, which are fast with the gear segments, are tilted in a direction to reduce their driving or propelling effect. The' rotary joint 99, I99 is such as to permit .free rotation Of'the spindle 98 upon the upper end of thB'SCICW- shaft 1921 while at the same timeimparting-vertical movementto the spindlecorrespondingwiththat ofzthe screw shaft. 1

For thefpurpose of. turning in the opposite direction, the pilot Will'tilt the handle- H11 to restore the blades :of theright rotor iii to driving position; the blades 'of'the'left rotor l9:.then being adjusted through the medium of the handle H8 to reduce their. driving. effort;v Similarly, the ship maybetrimmed by adjustingthe blades 80 of the rear rotor 20 about their/vertical a-xes'by tilting the-handles H! and H8: forwardly and; rearwardly.

For" the purposeof' vertical descent, the arms 30ofeach rotorhousing sleeve 26 arerestored .to an intermediate vertical position so that only liftingreffects are'obtained, thereby allowing the ship to'settle. It is possible, in parking. the ship, to'move-the same-rearward, to some. extentyby 'tippingthe arms 39 inthe opposite direction: so

as :to tipztheupper ends of the housings and the uppenend' of the axes of the rotors 18 rearwardathis also beingaccomplished by the pilot from the cockpit through the medium of the hand wheels 40 and'd'l and the cablesfil ,and32'. After .theeship. hasilanded, the clutch 59?" may 'be disengaged .to disruptythe drive to the several rotors IBIandZil.

It .willbecome apparent: to those skilled: in "the artithat many modifi'cationsmay be made in the structure.'-. and arrangement: of the various contitols. of; the'helicopter without departing from thelzspirit of :the invention. Therefore, it isintendedithat all modifications shall be protected asifall .within' the scope oftheappended claims.

I claim asmy invention: I

1. l'nahelicopterz a body havinga'longitudinal axisiofifiight; a rotor connected with said body andzprovidedwithlapair of radial blades normallydisposed. in'generally horizontal planes and revolvable about a vertical axis; and adjustable intereng'agingmeans connecting said blades sothat centrifugal force acting on either blade is counteracted by the centrifugal force 'applied" to the other blade, said interengaging means including: an eccentric element adjustable on each blade, 's'aidelements interlocking with their peripheries in contact. 7

2f In a helicopter: a body having a longitudinal axis'of flight; a rotor connected with said body and provided with a pair ofradial blades normallydisposed in generally horizontal planes and revolvable abouta vertical axis; and adjustable interengagingmeans connecting said blades so that centrifugal force acting on: either bladeis counteractedby the centrifugal force applied'to the other blade, said interengaging means includingan eccentric element on each blade, said elementsinterlocking with their peripheries in contact, .and .including adjusting means for adjusting saideccentrics angularly with respect to each othento movesaid blades toward and away from each;other in' aradial direction. 1

3. Inra helicopter: a body having a longitudinal axis; of flight; a rotor connected with said body and .proyided with radial blades normally disposed ingsnerally horizontal'planes and revolvable about auvertical axis with their longitudinal axes-:aligned:.and:with their inner ends spaced apart; a pair. of arms; operatively; connected. to each-blade at its-inner. end,,said; pairs. of? arms beingdisposed in crossingplanes'; a pin extending between .said arms of .each pair'of arms ;,an eccentric element carried by eachof saidpins, said elements-interlocking with their peripheries in contactso that centrifugal force acting upon either. of said blades is counteracted by centrifue galforce acting upon the other of said blades; and means for'adjustingsaid. eccentric elements angularly on said pins tov-ary the spacingbeapart; manually controlled means'fortilting said blades to vary their pitch; a pair of "arms operatively connected to'each blade at its innerend, said pairs of arms being disposed in crossing planes; a pin extending between said arms of each pair of arms; an eccentric element carried by each of said pins, said elements interlocking with theirperipheries in contact so that centrifugal force acting upon either of said blades is counteracted by centrifugal force acting upon the other of said blades; and means for adjusting said eccentric elements angularly on said pins to vary the spacing between the inner ends of said blades. 7. The combination as defined in claim 6*in which said eccentric elements consist ofelongate cylinders so that the peripheries thereof remain in contact regardless of'the relativeangulardisposition of said blades.

PAUL- M. LEWIS.

REFERENCES. CITED I I The following references are of record in the file of-thispatent:

UNITED STATES PATENTS;

Date

Number Name D. 144,401, Lewis .Apr. 9, 1946 1,622,138 Ellerman Mar. 22, .1927 1,783,011 Florine Nov. 25, 1930 1,844,786 Nelson .Feb. 9, 1932 1,891,272 Slonimsky Dec.:20, 1932 1,892,036 Campens Dec. 27, 1932 1,951,817 Blount Mar. 20, 1934 1,987,650 Wiegand Jan. 15, 1935 2,030,953 Gemeny Feb. 18,1936 2,146,367 Berliner Feb. 7, 1939 2,284,902 Hosford June 1942 2,32 ,572 Campbell ..June 15, 1943 2,330,842 Pullin Oct. 5., 19.43 2,405,488 Briner Aug. 6, .1946

FOREIGN PATENTS Number Country, Date 563,529 France Sept. 27, 1923 637,938 France Feb. 13, 1928 449,664 Great Britain Julyl, 1936 525,809 Great Britain Sept. 4, 1940 580,008 GreatBritain Aug; 23,1946 99,775 Sweden Sept.- 3', 1940 

